Rolls-Royce Peregrine - Design and Development

Design and Development

During the 1930s the use of superchargers to increase "effective displacement" of an aircraft engine came into common use. Charging of some form was a requirement for high-altitude flight, and as the strength of the engines improved there was no reason not to use it at all times. The introduction of just such a "ground-level" supercharger to the Kestrel along with several design changes improved the power-to-weight ratio considerably, and it was generally felt that the resulting Peregrine would be the "standard" fighter engine for the impending war. Following the company convention of naming its piston aero engines after birds of prey, Rolls-Royce named the engine the Peregrine after the Peregrine Falcon (Falco peregrinus), the world's fastest and most widespread bird of prey.

A design feature of the Peregrine was that it was produced in both right- and left-hand tractor variants. This was done to improve aircraft handling by providing a counter-rotating propeller facility. The handing of internal parts to achieve this was a considerable complication that was later abandoned in favour of an idler gear arrangement for the Merlin propeller reduction gear.

Four Kestrel/Peregrine cylinder banks attached to a single crankcase and driving a single common crankshaft would produce the contemporary Rolls-Royce Vulture, a 1,700-horsepower (1,300 kW) X-24 which would be used for bombers.

As it transpired, aircraft designs rapidly increased in size and power requirements to the point where the Peregrine was simply too small to be useful. Although the Peregrine appeared to be a satisfactory design, it was never allowed to mature since Rolls-Royce's priority was refining and producing the Merlin. As a result the Peregrine saw use in only two aircraft: the Westland Whirlwind and the Gloster F9/37. The Vulture was fitted to the Hawker Tornado and Avro Manchester, but proved unreliable in service. With the Merlin itself soon pushing into the 1,500 horsepower (1,100 kW) range, the Peregrine and Vulture were both cancelled in 1943, and by mid-1943 the Merlin was supplemented in service by the larger Rolls-Royce Griffon.